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        <section id="main"><article id="post-Dart-面向对象-OOP" class="article article-type-post" itemscope itemprop="blogPost">
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      Dart-面向对象(OOP)
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<p>所有的类都继承自 Object</p>
<h2 id="构造方法"><a href="#构造方法" class="headerlink" title="构造方法"></a>构造方法</h2><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line">//命名构造方法：[类名+.+方法名]</span><br><span class="line">//使用命名构造方法为类实现多个构造方法</span><br><span class="line">Student.cover(Student stu) : super(stu.name, stu.age) &#123;</span><br><span class="line">    print(&apos;命名构造方法&apos;);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">//命名工厂构造方法：factory [类名+.+方法名]</span><br><span class="line">//它可以有返回值，而且不需要将类的final变量作为参数，是提供一种灵活获取类对象的方式。</span><br><span class="line">factory Student.stu(Student stu) &#123;</span><br><span class="line">    return Student(stu._school, stu.name, stu.age,</span><br><span class="line">        city: stu.city, country: stu.country);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">///工厂构造方法演示</span><br><span class="line">class Logger &#123;</span><br><span class="line">    static Logger _cache;</span><br><span class="line"></span><br><span class="line">    //  工厂构造方法：</span><br><span class="line">    //  不仅仅是构造方法，更是一种模式</span><br><span class="line">    //  有时候为了返回一个之前已经创建的缓存对象，原始的构造方法已经不能满足要求</span><br><span class="line">    //  那么可以使用工厂模式来定义构造方法</span><br><span class="line">    factory Logger() &#123;</span><br><span class="line">        if (_cache == null) &#123;</span><br><span class="line">        _cache = Logger._internal();</span><br><span class="line">        &#125;</span><br><span class="line">        return _cache;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    Logger._internal();</span><br><span class="line"></span><br><span class="line">    void log(String msg) &#123;</span><br><span class="line">        print(msg);</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="set-和-get"><a href="#set-和-get" class="headerlink" title="set 和 get"></a>set 和 get</h2><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br></pre></td><td class="code"><pre><span class="line">// 可以为私有字段设置getter来让外界获取到私有字段</span><br><span class="line">String get school =&gt; _school;</span><br><span class="line"></span><br><span class="line">// 可以为私有字段设置setter来控制外界对私有字段的修改</span><br><span class="line">set school(String value)&#123;</span><br><span class="line">    _school = value;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="static"><a href="#static" class="headerlink" title="static"></a>static</h2><ul>
<li><p>使用 static 关键字来实现类级别的变量和函数</p>
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<li><p>静态成员不能访问非静态成员（ static 关键字修饰的成员 不能访问 非 static 关键字修饰的成员）</p>
</li>
<li><p>非静态成员可以访问静态成员</p>
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<li><p>类中的常量是需要使用 static const 声明</p>
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